Slugging the bore

[roscottjr]

Before I say anything else I just want to say I do know how to slug a bore. I have recently been told that simply slugging the bore does nothing. The guy in another group, to my knowledge he is not a member here but not positive, he claims that there are restrictions in every bore and that slugging the bore only tells you the smallest restriction. I personally feel he is just trying to cause trouble but my question is this. Does he have a point and to what extent does it matter? He claims it could be something as simple as where a barrel threads to the receiver. This is new to me. Is this something that will always make a difference or does it not matter at all? Does it only matter for rifle or competition? Any information would be great.

Thanks
Robert

[Mk42gunner]

My thoughts on slugging a bore.

While slugging a bore, (rifle, auto loader or revolver) doesn't tell you everything, it definitely tells you the smallest size of the barrel or cylinder. It gives you a minimum size for your boolits, some nominal bores are a bit oversize, and a too small bare lead projectile can be one of the causes of leading.

Sizing to the throat diameter is supposed to be better, but I have never done a chamber cast or pound slug yet.

For what it is worth, I size my .30 caliber boolits to .311" for most .30 cal cartridges with a supposed .308" groove diameter.

Robert

[cstrickland]

yes he is correct in some guns. Revolvers can have choke where the barrel threads into the frame, and even through the barrel . you will certainly feel a larger bore area when slugging. I can not say that I have seen a modern auto pistol barrel that had choke spots in it. but I certainly have not seen everything. What I feel it does it gives you a starting point. If you are slugging the barrel and it is tight the entire way, then loose at the middle or muzzle, then you have a larger spot there . I feel that is the reason to go 0.001" - 0.002" over.

Like I said it is a starting point. It cuts your learning curve and eliminates you shooting a .356 bullet in a .359 bore !! you go right to .360 and have a better fit

[Outpost75]

There is a great sticky on determining correct bullet size. It should answer all of your questions.